I am using HP Compaq desktop model dx6100m/p4-550/80hfc/512g/1
The sounddmax integrated digital audio driver I downloaded from HP's site (for Vista) worked fine with Windows 7 Beta. When I installed Windows 7 RC, build 7100, I lost sound all together! and none of the driners I tried works!!!
Personally i think that an upgrade wich was included in the RC , has a conflict with your sound card driver , and unffortunately you will have to wait for at least RC2.If you have downloaded the drivers from the official website there`s no solving for your problem ,at least for the moment.In time all brands will release Windows 7 drivers